1. Field of the Invention
The present invention relates generally to improvements in graphic image symbol storage systems, and more particularly pertains to new and improved memory mapping schemes for one-dimensional memory storage systems and a storage organization wherein one-dimensional storage systems are utilized in conjunction with other memory means to generate a graphic image or images to be displayed on a CRT screen.
2. Description of the Prior Art
Many different types of graphic memory storage systems including one-dimensional memory storage systems such as video disc, magnetic floppy disc and optical disc systems are used as storage for video game displays. The graphic image stored on a normal video disc memory system is stored and retrieved sequentially. In other words, the symbol for each graphic frame which contains all the data for a complete image to be displayed on a CRT for a fraction of a second are normally scanned for display on a CRT, one by one, at an approximate speed of 30 frames per second starting from the first frame to the 54,000th frame. It takes thirty minutes to run through all the frames for normal video disc models. The usual organization of the frames which determines the time flow of the story line of the display is that the frames of the lower numbers appear first. If frame jumps occur, in other words, there is a gap between sequential frames being displayed, there is a discontinuity in the story line.
Many video disc players have various jump sequence systems available besides a halt condition which gives access and displays a certain frame repeatedly. For convenience, we will call this halt condition the N:0 mode. For normal display, the frames are accessed one by one in sequential order. For convenience we will call this the N:1 mode. When the frames are being displayed sequentially in reverse order at normal speed we will call the N:-1 mode. The video disc players that have a fast scan mode generally operate by providing access to every fifth frame sequentially. For fast scan in the forward direction, we will call this mode the N:5 mode.
Considering the performance parameters of a typical video disc player, access to a particular frame can be accomplished without a delay becoming apparent to the viewer within a range of .+-.15 frames. In other words, the player can move approximately 15 frames in either direction within the blanking time. If access beyond 15 frames is required, a frame display time must be utilized. For example, if a jump sequence of the N:100 or N:-100 mode is used, the frame memory is accessable every other frame time because a frame and a blanking time is needed to move over the range of 100 frames. In this case, only 15 frames per second are displayed. Display quality is decreased due to flickering. This flickering, however, is tolerable and over a period of time becomes unnoticeable. The quality of the display can be improved somewhat by repeating display of the same frame twice during the time required for the jump. Whether this is done or not amounts to a tradeoff between quality and cost in a game environment.
Jump sequences are employed for special purposes such as fast scanning of the frames in memory, repeating the scene or backing up the time flow. These cases are not the normal game display procedure and viewers notice that the game play is abnormal any time display varies from the N:1 mode.
In a video game system, the hardware utilized includes control switches and/or levers for the players to operate. These control devices are used to change the relative dimensional relation between the player's symbol (such as his ship, man, etc.) and the surrounding symbols (such as enemies, roads, etc.). The switches and/or the levers manipulated by the player must provide an immediate response on the CRT. For instance, while driving a car on a road, if the player steers the control lever or steering wheel to the right, the player's car must go to the right of the road, while the road scene must move to the left, keeping his car steady on the CRT. In a shooting game, a bullet must be ejected from the gun immediately after the player actuates the firing button.
Conventional video games produce these effects by utilizing simple computer graphics of the symbol patterns on the CRT that are being changed in response to the manipulation of the controls. These are generated by the use of microprocessors and array memories. These computer graphics, however, are all cartoon style and far from the realistic appearance produced by movies or regular broadcast TV.
There have been video game systems on the market that employed both a computer graphics system and a video disc for the purpose of presenting a video game with a realistic background scene. In these hybrid systems a player's symbol was produced by the computer graphics hardware, while the rest of the scene, including objective patterns, were produced by the video disc system. The two images were simply displayed by superimposing one on the other. The varying locations of the objective patterns (such as enemies, road curves, etc.) in each frame were all memorized in the computer memory rather than in the video disc system, as was the position of the player's symbol. When a player's symbol and the moving objective patterns met on the screen, the disc frame was caused to jump to a separate series of frames to show an explosion or similar scene.
Since the video disc images and the images retrieved from computer memory were superimposed, the composite scene was not natural in many respects, such as shadows, relative sizes, reflection of light, color hues, brightness, color tone, etc. It was not natural also because the background scene changed constantly to a great extent, while the player's symbol remained fairly stationary. This type of hybrid system is also very expensive because it requires that the location of all the objective patterns in all the frames must be memorized by a computer memory rather than by the video disc memory. This greatly increases the cost of labor and hardware.
From the standpoint of the viewer or player, however, the defect of this system is that only a small part of the images being displayed is controllable by the manual controls operated by him. From the standpoint of appeal to a viewer/player it is more desirable that his control devices cause direct realistic changes on the screen. For example, if a whole playfield scene is controllable by a player as he actually views it from his ship, it is more attractive than if only the player's ship is controllable, while the rest of the scene simply moves along at its own pace, untouchable by the player.
The present invention solves the above-mentioned defects of a hybrid-type system and presents a video game display system at reasonable cost with realistic scenes from moves which utilize the full screen with wide and continuous variations according to the player's control at any given moment.